Myocardial Edema on T2-Weighted MRI

Importance of Evaluation of Ischemia/ Reperfusion Injury by Magnetic Resonance Imaging Although the advances in revascularization therapy have drastically decreased the mortality after ST-segment–elevation myocardial infarction (STEMI), the number of patients who develop heart failure after the reperfusion therapy continues to increase. More than 30% of the patients who survive STEMI develop heart failure long-term. Clinical studies have demonstrated that the larger infarct size (IS) and the resultant left ventricular dysfunction at the time of initial treatment significantly correlate with the likelihood of future adverse ventricular remodeling and arrhythmia. Thus, the efforts to minimize the IS by prompt reperfusion therapy is the primary rational in the treatment of STEMI in preventing heart failure and catastrophic cardiovascular events. Myocardial salvage determined by the initial perfusion defect, that is, myocardium at risk (MaR) and the final IS, is a surrogate marker of a successful reperfusion therapy to predict clinical outcome. Despite significant technological advances in the reperfusion therapy, myocardial reperfusion injury substantially decreases the myocardial salvage and increases the final tissue injury, which may account for ≤50% of the final IS. Even though various preor post-conditioning strategies, including stress (reversible ischemia, exercise, and hypothermia) and pharmaceutical intervention, may help to protect the heart from the ischemia/ reperfusion (I/R) injury, the efficacy of these treatments has not been sufficiently demonstrated in clinical studies. Thus, a robust imaging modality to assess the I/R injury and predict future cardiovascular events addresses a critical unmet clinical need.